대장용종의 임상적 중요성

배태석,정기훈,이준희,오민구,정병욱,배성한,안우섭 대한대장항문학회 2000 Annals of Coloproctolgy Vol.16 No.4

Limited Feasibility in Endovascular Aneurysm Repair Using Currently Available Graft in Korea

배태석,이태승,정인목,하종원,정중기,김상준 대한의학회 2008 Journal of Korean medical science Vol.23 No.4

Despite the wide acceptance of endovascular aneurysmal repair in patients with abdominal aortic aneurysm (EVAR), stringent morphologic criteria recommended by manufacturers may preclude this treatment in patients with AAA. The purpose of this study was to investigate how many patients are feasible by Zenith and Excluder stent graft system, which are available in Korea. Eighty-two AAA patients (71 men, mean age 70 yr) who had been treated surgically or medically from January 2005 to December 2006 were included. Criteria for morphologic suitability (MS) were examined to focus on characteristics of aneurysm; proximal and distal landing zone; angulation and involvement of both iliac artery aneurysms. Twenty-eight patients (34.1%) were feasible in Zenith stent graft and 31 patients (37.8%) were feasible in Excluder. The patients who were excluded EVAR had an average of 1.61 exclusion criteria. The main reasons for exclusion were an unfavorable proximal neck (n=34, 41.5%) and problem of distal landing zone (n=25, 30.5%). There was no statistical significance among gender, age or aneurysm size in terms of MS. Only 32 patients (39%) who had AAA were estimated to be suitable for two currently approved grafts by strict criteria. However, even unfavorable AAA patients who have severe co-mobidities will be included in EVAR in the near future. Therefore, more efforts including fine skill and anatomical understanding will be needed to meet these challenging cases.

가상기준점 기반 코드신호를 이용한 정밀 측위

배태석 한국측량학회 2011 한국측량학회지 Vol.29 No.2

With the increase in the number of smartphone users, precise 3D positional information is required by various applications. The positioning accuracy using civilian single-frequency pseudoranges is at the level of 10 m or so, but most applications these days are asking for a sub-meter level. Therefore, instead of an absolute positioning technique, the VRS-based differential approach is applied along with the correction of the double-differenced (DD) residual errors using FKP (Flächen-Korrektur-Parameter). The VRS (Virtual Reference Station) is located close to the rover, and the measurements are generated by correcting the geometrical distance to those of the master reference station. Since the unmodeled errors are generally proportional to the length of the baselines, the correction parameters are estimated by fitting a plane to the DD pseudorange errors of the CORS network. The DD positioning accuracy using 24 hours of C/A code measurements provides the RMS errors of 37 cm, 28 cm for latitudinal and longitudinal direction, respectively,and 76 cm for height. The accuracy of the horizontal components is within ±0.5 m for about 90% of total epochs,and in particular the biases are significantly decreased to the level of 2-3 cm due to the network-based error modeling. Consequently, it is possible to consistently achieve a sub-meter level accuracy from the single-frequency pseudoranges using the VRS and double-differenced error modeling. 스마트폰 사용자의 증가와 함께 다양한 응용분야에서 정밀한 3차원 위치정보가 요구되고 있다. 단일 주파수민간용 코드 자료를 이용한 위치결정 정확도는 10m 내외이지만, 향후 스마트폰 응용프로그램은 서브미터 수준의 위치정확도를 안정적으로 확보할 필요가 있다. 따라서 일반적인 절대측위 대신 가상기준점을 기반으로 하는상대측위 방식을 적용하였으며, 면보정계수를 이용하여 이중차분 오차를 보정하였다. 가상기준점은 로버 가까운 지점에 설정하고, 주 기준점 관측자료를 바탕으로 기하학적인 거리를 반영하였다. 이중차분으로 제거되지 않은 오차는 일반적으로 기선거리와 비례하므로, 로버 외부의 상시관측소 네트워크를 평면에 접합하여 면보정계수를 추정하였다. 이중차분 오차를 보정한 가상기준점과 로버의 24시간 C/A 코드 자료를 이용한 로버의 위치측정결과위도, 경도방향의 평균제곱근(RMS) 오차가 각각 37cm, 28cm 였으며, 높이 방향의 오차는 76cm 수준이었다. 또한 평면좌표의 성분별 오차는 전체의 약 90% 에서 ±0.5m 이내의 결과를 보였으며, 특히 네트워크 기반의오차모델링을 통해 평면좌표의 바이어스가 2-3cm 수준으로 크게 향상되었다. 따라서 가상기준점과 이중차분 오차모델링을 통해 단일 주파수 코드 자료로부터 안정적인 서브미터 정확도의 위치결정이 가능하다.

Distribution of the Colonoscopic Adenoma Detection Rate According to Age: Is Recommending Colonoscopy Screening for Koreans Over the Age of 50 Safe?

배태석,하윤형,김창균,이지현,하광일,신상현,이영철,강윤식 대한대장항문학회 2015 Annals of Coloproctolgy Vol.31 No.2

Purpose: This study was conducted to determine the distributions of the polyp detection rate (PDR) and the adenoma detection rate (ADR) according to age by analyzing the polypectomy results. Methods: A total of 10,098 patients who underwent a colonoscopy in 2013 were included in this study. Chi-square and logistic regression statistical analyses were performed using SPSS ver. 19. Results: The mean age of the patients was 52.7 years old (median, 54 ± 12.52 years; range, 14 to 92 years). A total of 6,459 adenomatous polyps (61.7%) from a total of 10,462 polyps were eliminated. The PDR was 50.9% (5,136/10,098), and the. ADR was 35.4% (3,579/10,098). The male-to-female ratio was 51.3%:48.7%, with a male-to-female ADR ratio of 42.8% : 27.7% (P < 0.001). In the age distribution, the values of the ADR were 0% for patients in their 10’s, 6.3% for those in their 20’s, 14.0% for those in their 30’s, 28.7% for those in their 40’s, 38.4% for those in their 50’s, 46.2% for those in their 60’s, 55.8% for those in their 70’s, 56.1% for those in their 80’s, and 33.3% for those in their 90’s. In males, the values of the ADR were 0%, 9.1%, 17.1%, 37.8%, 48.2%, 53.6%, 61.7%, 59.1%, and 33.3% for the same age distribution, and a steep increase was found between patients in their 30’s and patients in their 40’s. Significant (P < 0.001) factors influencing the ADR included sex, previous colonoscopy experience, polypectomy method, and age of more than 40 years. Conclusion: In considering the adenoma carcinoma sequence, 28.7% of people, especially 37.8% of males in their 40’s showed adenomatous polyps. Whether an earlier first-time colonoscopy will have better results in preventing colorectal cancer should be investigated and discussed.

GNSS관측 공공측량 정확도 분석 및 업무프로세스 제안

배태석 한국측량학회 2018 한국측량학회지 Vol.36 No.6

공공측량/통합기준점측량 작업규정은 기존 트래버스 측량 작업규정을 준용하고 있으며, GNSS관측 특성을 정 확하게 반하지 않아서 현장 작업과 자료처리에 어려움이 있다. 또한, GNSS관측 자료처리 절차에 대한 규정이 명 확하지 않고, 정확도 검증방법 역시 일반적인 기준과 차이가 있다. 본 연구에서는 현재 규정을 분석하고 적절한 업 무프로세스를 제안하기 위해 공공기준점 측량과 유사한 시나라오를 바탕으로 짧은 세션(30분) 데이터를 처리했다. 서울특별시 네트워크 RTK (Real Time Kinematic) 기준점에 대해서 3일간 동일한 시간대 결과를 비교했으며, 하루 중 시간에 따른 결과를 비교해서 전반적인 자료처리 정확도를 평가했다. 대류권 지연오차 추정여부에 따른 정확도 차이를 동시에 분석했으며, 추정결과는 24시간 정지측량 결과와 비교했다. 대류층 지연오차를 추정하는 것이 정확 도와 좌표안정성 향상에 유리하며, 평균제곱근오차는 대략 평면 5mm, 수직 1cm 수준으로 추정되었다. 본 연구결 과를 바탕으로 통합기준점을 포함한 동시관측 일간해를 추정하고, 이를 통합하여 최소제약조건을 통해 최종해를 결정하는 업무프로세스를 제안한다. 이를 위해서는 학술용 자료처리시스템을 이용한 자료처리자동화시스템이 구 축되어야하며, GNSS자료처리를 위해 통합기준점과 공공기준점 코드를 표준화해야 한다. Currently, the regulation and rules for public surveying and the UCPs (Unified Control Points) adapts those of the triangulated traverse surveying. In addition, such regulations do not take account of the unique characteristics of GNSS (Global Navigation Satellite System) surveying, thus there are difficulties in field work and data processing afterwards. A detailed procesure of GNSS processing has not yet been described either, and the verification of accuracy does not follow the generic standards. In order to propose an appropriate procedure for field surveys, we processed a short session (30 minutes) based on the scenarios similar to actual situations. The reference network in Seoul was used to process the same data span for 3 days. The temporal variation during the day was evaluated as well. We analyzed the accuracy of the estimated coordinates depending on the parameterization of tropospheric delay, which was compared with the 24-hr static processing results. Estimating the tropospheric delay is advantageous for the accuracy and stability of the coordinates, resulting in about 5 mm and 10 mm of RMSE (Root Mean Squared Error) for horizontal and vertical components, respectively. Based on the test results, we propose a procedure to estimate the daily solution and then combine them to estimate the final solution by applying the minimum constraints (no-net-translation condition). It is necessary to develop a web-based processing system using a high-end softwares. Additionally, it is also required to standardize the ID of the public control points and the UCPs for the automatic GNSS processing.

Parametric Analysis of the Solar Radiation Pressure Model for Precision GPS Orbit Determination

배태석 한국측량학회 2017 한국측량학회지 Vol.35 No.1

The SRP (Solar Radiation Pressure) model has always been an issue in the dynamic GPS (Global Positioning System) orbit determination. The widely used CODE (Center for Orbit Determination in Europe) model and its variants have nine parameters to estimate the solar radiation pressure from the Sun and to absorb the remaining forces. However, these parameters show a very high correlation with each other and, therefore, only several of them are estimated at most of the IGS (International GNSS Service) analysis centers. In this study, we attempted to numerically verify the correlation between the parameters. For this purpose, a bi-directional, multi-step numerical integrator was developed. The correlation between the SRP parameters was analyzed in terms of post-fit residuals of the orbit. The integrated orbit was fitted to the IGS final orbit as external observations. On top of the parametric analysis of the SRP parameters, we also verified the capabilities of orbit prediction at later time epochs. As a secondary criterion for orbit quality, the positional discontinuity of the daily arcs was also analyzed. The resulting post-fit RMSE (Root-Mean-Squared Error) shows a level of 4.8 mm on average and there is no significant difference between block types. Since the once-per-revolution parameters in the Y-axis are highly correlated with those in the B-axis, the periodic terms in the D- and Y-axis are constrained to zero in order to resolve the correlations. The 6-hr predicted orbit based on the previous day yields about 3 cm or less compared to the IGS final orbit for a week, and reaches up to 6 cm for 24 hours (except for one day). The mean positional discontinuity at the boundary of two 1-day arcs is on the level of 1.4 cm for all non-eclipsing satellites. The developed orbit integrator shows a high performance in statistics of RMSE and positional discontinuity, as well as the separations of the dynamic parameters. In further research, additional verification of the reference frame for the estimated orbit using SLR is necessary to confirm the consistency of the orbit frames.

말단 회장부의 악성 림프종에 의한 장중첩증 1예 보고

배태석,조종섭,정기훈,정병욱,배성한,서정욱 대한외과학회 1997 대한외과학회 학술대회 초록집 Vol.1997 No.11

대장 용종의 임상적 중요성

배태석,정기훈,이준희,오민구,정병욱,배성한,안우섭,서정욱 대한외과학회 2000 대한외과학회 학술대회 초록집 Vol.2000 No.5

가우스-헬머트 모델 전최소제곱: 평면방정식과 측지좌표계 변환

배태석,홍창기,임수현,Bae, Tae-Suk,Hong, Chang-Ki,Lim, Soo-Hyeon 한국측량학회 2022 한국측량학회지 Vol.40 No.4

일반적인 조정계산에서는 독립변수의 오차는 없다고 가정하고 종속변수의 오차만을 고려하는 최소제곱해를 구한다. 그러나 지상측량에 의해 결정한 3차원 공간좌표나 GNSS (Global Navigation Satellite System) 기반 추정좌표는 성분별로 독립적으로 결정되지 않으므로 모든 성분에 오차가 있을 뿐만 아니라 공분산도 존재한다. 따라서 좌표쌍을 이용한 평면 추정이나 좌표계 변환에서는 모든 성분의 오차를 고려하는 전최소제곱을 적용해야 한다. 이를 위한 다양한 모델이 존재하며, 특별한 제약조건을 제외하면 동등한 해를 제공한다. 본 연구에서는 가우스-헬머트 모델(GHM: Gauss-Helmert Model) 기반 전최소제곱으로 VLBI 타겟이 형성하는 자취를 이용하여 평면의 법선벡터를 추정했으며, 지역좌표계를 세계측지계로 변환하는 계수 결정에도 적용했다. 평면방정식의 경우 기존 최소제곱 방법과 비교해서 법선벡터는 동일하지만 분산요소의 안정성과 타겟 위치에 따른 분산요소 특성을 명확히 확인할 수 있었다. 좌표계 변환계수는 가우스-헬머트 모델을 적용하면 변환 전후 두 좌표계에서 모두 잔차를 계산할 수 있으며, 기존 방식보다 잔차가 더 작아진다. The conventional LESS (LEast-Squares Solution) is calculated under the assumption that there is no errors in independent variables. However, the coordinates of a point, either from traditional ground surveying such as slant distances, horizontal and/or vertical angles, or GNSS (Global Navigation Satellite System) positioning, cannot be determined independently (and the components are correlated each other). Therefore, the TLS (Total Least Squares) adjustment should be applied for all applications related to the coordinates. Many approaches were suggested in order to solve this problem, resulting in equivalent solutions except some restrictions. In this study, we calculated the normal vector of the 3D plane determined by the trace of the VLBI targets based on TLS within GHM (Gauss-Helmert Model). Another numerical test was conducted for the estimation of the Helmert transformation parameters. Since the errors in the horizontal components are very small compared to the radius of the circle, the final estimates are almost identical. However, the estimated variance components are significantly reduced as well as show a different characteristic depending on the target location. The Helmert transformation parameters are estimated more precisely compared to the conventional LESS case. Furthermore, the residuals can be predicted on both reference frames with much smaller magnitude (in absolute sense).

실시간 GPS 위치결정 정확도 향상을 위한 가상기준점 코드신호 보정

배태석(Bae, Tae-Suk),김수경(Kim, Su Kyung) 한국측량학회 2011 한국측량학회 학술대회자료집 Vol.2011 No.4